The Development of a Technique for Sensitizing Cells of Various Origins for Biotechnological Purposes

The functional activity stimulation of cell cultures was tested in MDBK cell culture, photobacteria AliivibriofischeriandHalobacteriumhalobium. Theaim of the investigation was to increase the ”yield” of the cells using an environmentallysafe stimulant and membrane-tropic agent that isalso safe for the experimenter. Ultrasonicwaves were used.Experimental ultrasonic exposure varied within the following limits: time from 1 to 300 sec, SATA-intensity of 0.01–2.0 W/cm2, generation frequency of 0.88 or 2.64 MHz, standing or traveling wave. The modulation frequency range was within 0.1–150 Hz. The devices used were: UST-1-01F, UST-5 and UST1.02C. The modulating generators were G3–112 and CP–110.Stimulation of MDBK cell growth was initiated by US-intensity of 0.03–0.05 W/cm2 , with an exposure of 5–30 sec.Exposure to ultrasound with an intensity of 0.2–0.4 W/cm2 (for 3 min) had a stimulating effect on bioluminescence and was associated with an increase in the growth rate ofA. fischeri. The findings indicated that 0.4 W/cm2ultrasonic intensity and modulation frequencies from 0.25 to 0.7 Hz can stimulate the growth of archaea.It was revealed that the maximum proliferation index in all cases of stimulant application was noted in cultures with minimal initial proliferative activity in the control.The authors expect thatthese results on the possibilities of acoustic continuous and modulated waves can be applied for biotechnological purposes to develop a new biotechnological method. Keywords: cell culture, ultrasound, proliferation, stimulation

Electrowetting Induced Droplet Generation in T-junctions

In the current study, droplet generation in a T-junction fluidic channel device was studied through using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver-Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in decrease in the size of droplet with increasing the velocity ratios. In shearing regime, the effectiveness of electrowetting on the droplet generation frequency as well as droplet size is visible in a T-junction fluidic channel since after applying voltages, specified with non-dimensional electrowetting numbers of ?=0.5 and 1.2, dispersed phase is pulled out into the oil phase. In fact, with applying the voltage on the top wall, the droplet breakup time was decreased and smaller droplets were produced. Finally, different important parameters such as pressure difference across the interface as well as Shear Stress exerted from the continuous phase shear stress were examined in a detail.

A Waveguide Ultrasonic Phased Array Radar for High Temperature Equipment Monitoring

This paper proposes a design for monitoring high temperature structures utilizing phased array waveguide transducers, where the active sensing elements work synthetically together to achieve damage detection. The waveguide transducer is comprised of a wave-generation piezo element and a waveguide bar conducting the wave energy into the host structure. A coupled-field local finite element model (FEM) is constructed to grasp an in-depth understanding of the wave generation behavior. Via the harmonic analysis, optimum wave generation frequency and mode type can be analyzed. Thereafter, an array of waveguide transducer elements are attached to the host structure to study their wave manipulating ability. The system works based on the principle of phased array theory; the excitation instant of each element is controlled to form an equiphasic surface. In this way, the wave propagation phenomenon such as focusing and directional steering can be realized. An ultrasonic radar for high temperature working condition can thus be realized. The proposed system possesses great application potential to enhance the performance of Lamb wave SHM and NDE systems for high temperature structures.

Normal levels of ribosome-associated chaperones cure two groups of [PSI+] prion variants

The yeast prion [PSI+] is a self-propagating amyloid of the translation termination factor, Sup35p. For known pathogenic prions, such as [PSI+], a single protein can form an array of different amyloid structures (prion variants) each stably inherited and with differing biological properties. The ribosome-associated chaperones, Ssb1/2p (Hsp70s), and RAC (Zuo1p (Hsp40) and Ssz1p (Hsp70)), enhance de novo protein folding by protecting nascent polypeptide chains from misfolding and maintain translational fidelity by involvement in translation termination. Ssb1/2p and RAC chaperones were previously found to inhibit [PSI+] prion generation. We find that most [PSI+] variants arising in the absence of each chaperone were cured by restoring normal levels of that protein. [PSI+] variants hypersensitive to Ssb1/2p have distinguishable biological properties from those hypersensitive to Zuo1p or Ssz1p. The elevated [PSI+] generation frequency in each deletion strain is not due to an altered [PIN+], another prion that primes [PSI+] generation. [PSI+] prion generation/propagation may be inhibited by Ssb1/2/RAC chaperones by ensuring proper folding of nascent Sup35p, thus preventing its joining amyloid fibers. Alternatively, the effect of RAC/Ssb mutations on translation termination and the absence of an effect on the [URE3] prion suggest an effect on the mature Sup35p such that it does not readily join amyloid filaments. Ssz1p is degraded inzuo1Δ [psi-] cells, but not if the cells carry any of several [PSI+] variants. Our results imply that prions arise more frequently than had been thought but the cell has evolved exquisite antiprion systems that rapidly eliminate most variants.

Droplet Generation in a Flow-Focusing Microfluidic Device with External Mechanical Vibration

The demand for highly controllable droplet generation methods is very urgent in the medical, materials, and food industries. The droplet generation in a flow-focusing microfluidic device with external mechanical vibration, as a controllable droplet generation method, is experimentally studied. The effects of vibration frequency and acceleration amplitude on the droplet generation are characterized. The linear correlation between the droplet generation frequency and the external vibration frequency and the critical vibration amplitude corresponding to the imposing vibration frequency are observed. The droplet generation frequency with external mechanical vibration is affected by the natural generation frequency, vibration frequency, and vibration amplitude. The droplet generation frequency in a certain microfluidic device with external vibration is able to vary from the natural generation frequency to the imposed vibration frequency at different vibration conditions. The evolution of dispersed phase thread with vibration is remarkably different with the process without vibration. Distinct stages of expansion, shrinkage, and collapse are observed in the droplet formation with vibration, and the occurrence number of expansion–shrinkage process is relevant with the linear correlation coefficient.